1. Field of the Invention
The present invention relates generally to structural concrete building blocks. More particularly, the present invention relates to molded light weight large concrete blocks used for constructing external walls and retaining walls as well as form-work in load bearing walls and that is easily reinforced in horizontal and vertical directions.
2. Description of the Prior Art
Concrete blocks used for constructing walls generally require mortar to adhere one block to another. Consequently, walls and other structures assembled from conventional blocks are often expensive and labor intensive to build and maintain. Additionally, conventional blocks may not be used for form work.
In order to eliminate the use of mortar, self linking blocks have been constructed utilizing different systems of interconnecting tongues and grooves. Such interconnecting blocks are generally of limited size and are generally too heavy to be of practical use. Additionally, presently available interconnecting blocks often have poor thermal insulation properties, are not sufficiently strong to be used as form-work and do not have internal cavities designed to facilitate the placement of insulation, reinforcing members, pipes or conduits.
In an effort to create interconnecting blocks that are lightweight and have high thermal resistivity, some presently available interconnecting blocks are constructed from polystyrene. However, polystyrene is flammable, emits toxic vapors and is expensive to transport. Additionally, polystyrene is often not receptive to finishing with plaster or gypsum and the blocks must often be treated with bonding agents prior to finishing. These disadvantages render presently available interconnecting blocks impractical for many applications.
For example, a system marketed under trademark MEP consists of a polystyrene panel reinforced with wire mesh trusses spaced 6" on center and with wire mesh reinforcement on the two faces of the polystyrene panel. The external faces are covered by a plaster layer 7/8" thick. The MEP provides a highly insulated wall that is structurally strong and can be easily constructed. However, it has a few drawbacks. It limits the work to only external walls in building construction, and it is not a cheap alternative.
Consequently, a need exists for lightweight building blocks that have high thermal insulating properties, and strong construction, that do not give off toxic fumes, and that incorporate internal cavities.
Several U.S. patents disclose modular building blocks. These include U.S. Pat. Nos. 3,764,357; 3,936,987; 4,001,988; 4,016,693; 4,098,040; 4,268,317; 4,314,431; 4,372,091; 4,490,075; and 4,905,439.